seam-carving

How to perform seam carving on an image using PHP's GD library?

I am working on a project that resizes images using PHP's GD library. I would like to be able to add the option to use seam carving to resize images but don't want to require something like ImageMagick (which can do seam carving with its liquid rescale feature) to accomplish this. Since there are no built-in seam carving functions in GD...

What is a seam (Seam-carving)

I am reading the paper about seam carving for resizing an image. Down on page 3 where they define a seam mathematically, I need help clarifying it. The paper says that a seam is an 8-connected path of pixels. How can it be 8-connected if the pixel cannot be on the same row? Shouldn't it be 3-connected? http://www.seamcarving.com/arik/...